I have however not seen any proof that it benefits the country other than employment (how are the salaries?).
If you look at tax revenue as percent of GDP it's almost had a freefall [1], which could be okay if the GDP is high enough.
In direct numbers however Ireland as of 2014 was not even back to 2007 levels in tax revenue (pre economic crisis) [2], and ignoring inflation. And only counting corporation tax, not even back to 2002 levels.
[1] http://data.worldbank.org/indicator/GC.TAX.TOTL.GD.ZS?locati...
[2] https://en.wikipedia.org/wiki/Corporation_tax_in_the_Republi...
Both of your observations address the latter, while I made the former.
Looking straight at GDP (even if it's a blunt instrument), Ireland hasn't reaped a lot of rewards there either [1].
And their growth over the past few years appears to be back to pre-crisis speed.
That page allows displaying both on the same graph (compare to "US GDP") and when placed by side by side it's easy to see that Ireland has grown at least twice as quickly since 1995.
https://www.theguardian.com/world/2015/mar/05/ireland-attrac...
> A major draw for US firms is Ireland’s low 12.5% corporation tax rate and numerous controversial tax breaks. The government has promised to phase out the latter.
> The corporate tax rate, which remains a sacrosanct part of Irish industrial policy, has been so successful in wooing US investment that the country’s neighbours across the border want it too. The Northern Ireland assembly passed legislation this week allowing for corporation tax powers to be devolved, with politicians at Stormont aiming for a similar rate.